1. Field of the Invention
This invention relates to shutoff mechanism operated automatically in case of an emergency which produces excessive vibration or shaking, such as caused by an earthquake.
2. Problem
Violent shaking, such as produced by an earthquake, explosion concussion or impact jar, can disrupt pipelines, such as for gas, gasoline, oil, acid, caustic liquid or water, or even electric lines. A spark from a broken electric line could ignite gas escaping from a broken gas line, for example, to augment the damage that might be caused by the shock of an earthquake itself. Under such circumstances it is desirable to shut off the flow of gas, gasoline or oil from a broken pipeline to prevent fire, acid or caustic fluid from a broken pipeline to prevent damage and even the escape of water from a broken pipeline to prevent flooding.
Emergency shutoff mechanism has been proposed in the past to shut valves in fluid lines automatically in response to excessive vibration, such as caused by an earthquake, but such prior devices have had disadvantages or lacked advantages of the apparatus of the present invention.
3. Prior Art
U.S. Pat. No. 4,207,912, issued June 17, 1980, shows an emergency shutoff valve intended to shut off the supply of gas in the event of an earthquake of predetermined magnitude. The mechanism of this patent, however, does not provide for adjustment to enable operation of the mechanism to be effected upon being subjected to different degrees of vibration or shock.
U.S. Pat. No. 4,116,209, issued Sept. 26, 1978, discloses a shock-actuated shutoff valve, but this mechanism does not utilize a permanent magnet, and it would probably be difficult to reset the mechanism after an emergency shutoff actuation.
U.S. Pat. No. 3,783,887, issued Jan. 8, 1974, also discloses valve mechanism for gas and oil pipelines that would be shut off automatically by a predetermined degree of vibration, such as produced by an earthquake, but this mechanism does not provide an arrangement for altering the sensitivity of the mechanism to different degrees of vibration, and no provision appears to be made for resetting the valve to its upper position after it has dropped to closed position.
U.S. Pat. No. 3,360,007, issued Dec. 26, 1967, shows a mounting for a permanent magnet that is elevationally adjustable, but such adjustable magnet-supporting mechanism is not used in a vibration-actuated emergency shutoff mechanism.
U.S. Pat. No. 2,927,592, issued Mar. 8, 1960, discloses a shock or vibration emergency shutoff valve mechanism, but such mechanism does not utilize a magnet, and it is necessary to provide an additional control valve of some type in order to reset the valve necessary to remove an access door on the valve casing in order to gain access to the valve for resetting it, which would enable gas to escape from the casing.